Most AI video is silent, and the sound is added afterwards by a second model that never saw the picture. LTX-2.5 makes both at once.

A 22 billion parameter asymmetric dual stream diffusion transformer that generates video and audio jointly through bidirectional cross attention. Native multishot scenes, automatic duration and 4K HDR output. It handles text to video, image to video, video to video, text to audio and audio to video. A distilled build makes a ten second clip in roughly six to eight seconds on NVIDIA superchips. The text encoder is Gemma 4 12B. Open weights, with commercial use free under $10m of revenue.

Why this one is different

Joint generation is the whole claim. Adding sound afterwards gives you audio that approximately matches, which is why so much generated video has footsteps landing slightly wrong. Generating both from one model, with each conditioned on the other, is a harder problem and the reason lip movement and impact sounds line up. Shipping that as open weights, with a day one ComfyUI integration, puts it somewhere the closed video models are not.

Adding the sound afterwards is why so much generated video has footsteps landing slightly wrong.

How we got here

1. 2024Text to video becomes usable, and silent. Audio is a separate pipeline bolted on later.
2. 2025 to 2026Veo and Sora add native synchronised audio, and keep the weights closed.
3. 11 Aug 2026LTX-2.5 releases open weights doing joint video and audio, into ComfyUI on day one.

What it does and does not mean

Free under $10m of revenue is a revenue gate, not an open source licence, and the threshold is the vendor's to move. The six to eight second figure is also for a distilled model on NVIDIA superchips, which is not what most people have. And joint generation is a claim about architecture that nobody outside has independently measured. What is real is availability: the first competent open weight video model with sound, which changes who can make this rather than how good it gets.